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Microplastics are able to travel thousands of miles because of their shape

Microplastic particles, even at the most remote corners of our planet, have become a matter of concern. The mystery lies in how these relatively large and predominantly fiber-like microplastics travel, reaching places like Arctic glaciers and ice sheets.

Atmospheric transport models suggest that such large particles would typically fall out of the atmosphere near their sources.

To shed light on this paradox, an interdisciplinary group of scientists from the University of Vienna, Austria, and the Max Planck Institute for Dynamics and Self-Organization in Göttingen, Germany, conducted an intriguing study that combined laboratory experiments and model simulations.

Dynamics of traveling microplastics

In the laboratory experiments overseen by Mohsen Bagheri of the Max Planck Institute for Dynamics and Self-Organization, the team focused on understanding the settling dynamics of microplastic fibers traveling in the atmosphere.

Surprisingly, the literature had very little data on this topic, primarily due to the challenges involved in conducting controlled experiments on such tiny particles.

The team capitalized on advancements in submicron-resolution 3D printing and developed a novel experimental setup to track individual microplastics in the air.

Through their experiments, they discovered that microplastic fibers settle significantly slower than spheres of the same mass.

Bagheri notes, “With advances in submicron-resolution 3D printing and the development of a novel experimental setup that allows tracking of individual microplastics in air, we were able to fill this knowledge gap and improve existing models in this study.”

The path of non-spherical particles

To further investigate the microplastic travel phenomenon, the researchers integrated a model describing the settling process of non-spherical particles into a global atmospheric transport model.

The differences between spherical and fiber-like microplastics travel were stark. The model revealed that fibers with lengths of up to 1.5 mm could reach the most remote regions of Earth, while spheres of the same mass settled much closer to their plastic source regions.

Daria Tatsii is the first author of the study and a member of the Department of Meteorology and Geophysics at the University of Vienna.

“With the novel laboratory experiments and modelling analysis, we certainly reduce uncertainties about the atmospheric transport of fibers and can finally explain via modelling why microplastics reach very remote regions of the planet,” Tatsii explained.

“An important result of the study is that our analysis is applicable not only to microplastics, but also to any other particles such as volcanic ash, mineral dust, and pollen.”

Implications of microplastics long-distance travel

The study’s findings have broad implications for our understanding of atmospheric processes and potential environmental risks.

The model indicated that plastic fibers could reach greater heights in the atmosphere than spheres of the same mass.

Andreas Stohl is the study’s initiator and a researcher from the University of Vienna. He highlights the potential consequences.

“This could have implications for cloud processes and even for stratospheric ozone since it seems possible that microplastic fibers are abundant in the upper troposphere and might even reach the stratosphere. For instance, we cannot rule out that chlorine contained in these particles is harmful to the ozone layer,” Stohl said.

“However, right now, we do not even know how much plastic, and in which sizes and shapes, is emitted into the atmosphere, and we also do not know what happens to it under the extreme conditions of the upper troposphere and stratosphere. We are lacking very basic data. But given the dramatic increase in global plastic production, we have to be watchful,” Stohl concluded.

Unique shapes of microplastic particles

Amidst the uncertainties surrounding microplastics, one thing is clear: the distinct shapes of these particles must be considered when evaluating their environmental impact.

Their research highlights the importance of addressing the complex dynamics of microplastic fiber settling and their potential implications in atmospheric processes and ozone depletion.

By combining innovative laboratory experiments with advanced modeling techniques, the researchers have made significant strides in unraveling the mysteries surrounding the global travel of microplastic particles.

However, further research and data collection are necessary to fully understand the extent of plastic pollution and its impacts on our environment.

What the future holds

In summary, the study sheds light on the surprising journey of microplastics to some of the earth’s most remote regions.

Through laboratory experiments and modeling, the scientists unveiled the slower settling rates of fiber-like microplastics compared to spherical particles of the same mass.

These findings, combined with the potential for microplastic fibers to reach great heights in the atmosphere, introduce implications for cloud processes and the depletion of the ozone layer.

With the ever-increasing production of plastic, it is crucial to gather more data and conduct further research to mitigate the environmental risks associated with microplastic pollution.

As we strive to protect our planet’s delicate ecosystems, it is evident that the peculiar shapes of microplastic particles cannot be neglected in our investigations.

The full study was published in the journal Environmental Science & Technology.


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